Casting mold with steam-heated water jacket

ABSTRACT

A process and moulds are described for moulding large slablike building elements from pre-heated concrete in which the moulds are heated by controlled injection of steam into voluminous water-filled cavities in the moulds regulated to keep the mould temperature at or near the desired concrete hardening temperature.

Hummelshoj f I I A. [111 0 3,822,855 1451" July 9,1974

[22], Filed:

[ CASTING MOLD WITH STEAM-HEATED WATER JACKET [75] Inventor: Gustav ErikHununelshoj,

Bagsvaerd, Denmark [73] Assignee: Thomas Schmidt A/S, Bagvaerd,

Denmark Mar. 3, 1972 21 Appl. 190.; 231,473

[30] Foreign Application Priority Data Mar. 15, 1971 Denmark 1222/71[52] U.S. Cl .L 249/79, 249/81, 249/120,

249/161 [51] Int. Cl 822d 27/04 [58] Field of Search 249/79, 81, 78,111; 425/170; 165/108, 169

[56] References Cited UNITED STATES PATENTS 2 ,2 39, 1 9 5 4/1941Henderson 249/79 2,602,210 7/1952 Rumble 249/79 2,632,088 3/1953 Meyricket-al 249/78 X- 2,63 7,l98 5/1953 Spangler 425/170 X 3,124,627 3/1964Hood 3,251,405 5/1966 'Hallstriim 3,441,243 4/1969 Walz..-.

Saunders 249/79 X Primary Examiner -Robert D. Bladwin AssistantExamine'rJohn McQuade [57] ABSTRACT A process and moulds are describedfor moulding large slablike building elements from pre-he'ated concretein which the moulds are heated by controlled injection of steam intovoluminous water-filled cavities in the moulds regulated to keep themould temperature at or near the desired concrete hardening temperature.

5 Claims, Driawing Figures PATENTED JUL 9'974 $22,855

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SHEET 2 OF Q PATENTEDJUL 9:914

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PATENTEDJUL 91m $8355 SHEET 3 0F 4 It is known that the hardening ofcast concrete bodies, such as concrete elements for building purposes,can be promoted by the concrete being poured in a warm state, e.g., byheating the materials during processing in the concrete mixer. Thismethod possesses advantages over other known methods for heathardeningin which the concrete bodies are heated in the moulds after pouring.

Similar conditions prevail in casting other hardening masses, but sincethe invention is of greatest interest in concrete casting, andparticularly in production of concrete elements, it will in thefollowing be described in connection herewith, without any intention oflimiting the scope of application and usefulness of the invention.

If any advantages are to be gained by the use of preheated concrete itis, however, necessary that the poured concrete shall not immediatelyloose its heat to the relatively cold metal mass of the mould. A largeconcrete element mould has a metal mass which is at least equal to themass of the poured concrete, and as the specific heat of steel is about0.11 kilocalories/C/kg, while the concrete has a specific heat of about0.24 kilocalories/C/kg, varying slightly according to its composition, aconcrete mass poured at e.g. 60 may in a short time be cooled to about40C by a mould with an initial temperature of about As the rate ofhardening is doubled or halved every time the temperature of theconcrete is increased or reduced by 10C resp., it will be obvious thatthe hardening effect in the said case will be reduced to one fourth,which means that the hardening time will be multiplied by four. It isalso important that the heat of the concrete mass is well preservedduring the hardening process, both its initial heat content and the heatdeveloped during the hardening process, without any risk of localoverheatings. With a view to this, it is known to equip the moulds withcavities into which steam is blown directly and condenses on thesurfaces which define the mould and form the pouring cavity of theassembled mould, but as the steam must necessarily have a temperature ofl001l0C, the mould surfaces will be heated to too high temperatures,which may lead to local damage to the concrete element during thehardening process due to heat stresses and due to the fact that adjacentto the hot mould surfaces steam bubbles are formed, which mar thesurface of the elements.

All these difficulties are overcome by the apparatus according to theinvention for steam-heating casting moulds for hardening masses,particularly concrete. The invention is characterized in that the steamis introduced into water-filled cavities in the casting moulds.

By this means, the possibility is obtained of a rapid and effectiveheating of the moulds to the desired temperature without risk ofoverheating, the transmission of heat from the steam supplied to themould occurring very quickly and effectively by the condensation of thesteam in the water-filled cavities which ensures that the steam will notget into direct contact with the surfaces of the mould; moreover, thecontent of warm water in the cavities provided for that purpose in themoulds represents a considerable heat reserve, the specific heat of thewater being about nine times the specific heat of the metal mass of themould and four times the specific heat of the concrete,.so that thelatent heat of the water can compensate for the loss of heat which willoccur to the surroundings when the mould is left after the pouring, fromthe surface of the concrete as well as from the surface of the mould,whether the environment is the manufacturing shed itself or a hardeningchamber in which, by other means, a relatively high temperature isproduced and maintained.

The introduction of steam into the water-filled cavities may accordingto an embodiment of the invention commence prior to the pouring, so thatthe relevant mould parts have in advance been brought up to or close tothe desired hardening temperature. In this manner cooling of theconcrete on pouring into the moulds with adesired hardening temperatureis avoided, and at the same time a shortening of the time necessary forthe total casting process is obtained, the preliminary heating of themoulds taking place so quickly and simply that it can be performedsimultaneously with the other preparatory operations, such as cleaningand oiling and possibly assembling of mould parts into a mould ready forpouring.

As mentioned above, the invention also comprises a casting mould for usein performing the method, characterized by cavities for holding waterand by means for blowing steam into this water.

These means may according to the invention. consist of an injector whichis adapted to set up a circulation of the water in the said cavities bythe injection of steam. By this means is achieved, firstly, a rapid andeffective mixing and condensation of the steam into the water and,secondly, a rapid distribution of the supplied heat over the whole ofthe mass of water at disposal, which results in a quick and uniformthorough heating of the mould.

The condensate formed constitutes an addition to the mass of waterpresent in the water-filled cavities of the mould, and, consequently,the mould is according to the invention provided with one or moreoverflow means through which excess water may flow off. For practicalreasons, such overflow means should be closedas long as steam supplydoes not take place, and they are therefore advantageously according tothe invention designed in the form of outwardly opening automaticvalves.

Moreover, the mould according to the invention may advantageously beprovided with one or more temperature measuring points, e.g. thermometerpockets, at points where the temperature of the water represents thetemperature of the cast body during the hardening process. By this meansit becomes possible to watch the course of the hardening process bykeeping an eye on the temperature at the selected points.

The invention is illustrated in the drawing in which FIG. 1diagrammatically shows a section through a mould, suited for carryingout the method, in section on line I-I in FIG. 2,

FIG. 2 shows a section on line II--II in FIG. 1,

FIG. 3 shows another embodiment of a mould according to the invention insection on line III-III in FIG. 4, and

FIG. 4 shows the same as is shown in FIG. 3 on line IVIV in FIG. 3.

The mould shown in FIGS. l and 2 is intended for producing largeplate-shaped building elements of concrete by a number of such moulds 5being assembled into a battery in which the interstices between themoulds constitute pouring cavities and must be supposed to haveboundaries along the bottom and on the sides, such as separately fittedside pieces and end mould parts, not shown, e.g., in the form ofU-shaped frames accommodated in the interstices between the individualmoulds 5.

In the example shown it is assumed that the moulds rest on wheeledbogies 6 and are displaceable thereon along a wheel track which mayserve as transport or production line.

Each mould consists of a substantially rectangular plate with faceplates 3 which delimit the pouring cavities, into which concrete 1 hasbeen shown poured in FIG. 2. This illustration is purely disgrammatical,the concrete bodies produced being normally cast around a reinforcement,and it is possible to give the bodies any desired profile bycorrespondingly profiling the plates 3.

The mould delimiting plates 3 are stayed in relation to each other bymeans of sections 4 of steel, and between them, water jackets 2 areprovided in the form of closed cavities which during the operation arefilled with water.

Prior to or during the pouring of concrete the water in the waterjackets 2 is heated by steam being blown in through connection nipples 7and adjoined injectors 8 adapted to impart, by the steam injection, apowerful circulation to the water in the water jackets, as indicated byarrows in FIG. 1. As explained above, this results in a very rapid anduniform heating of the mass of water present and thereby of the mould,so that, when the concrete is being poured, the mould already has thetemperature at which it is desired that the hardening should take place.

In the embodiment shown in FIGS. 1 and 2 it is obvious that the batteryconstituted by the moulds will during the hardening process have acomparatively small free surface for emitting heat to the surroundingsThe heat emission will substantially occur along the outer edges of themoulds, and consequently, the water jackets are chiefly placed there.The hardening process proper is exothermic, but not sufficiently so tokeep step with the emission of heat which would take place to thesurroundings, but which is now compensated for by the heat contained inthe water masses, which heat may be supplemented also during thehardening process by additional steam injection; thus, the concrete caneasily during the entire hardening period be kept at a desired hardeningtemperature which may e.g., be over 60C.

In order to avoid an excess pressure in the water jackets the latter areprovided with an overflow means 9, through which excess water derivingfrom the condensation of the supplied steam can drain off freely.

To control the course of the hardening process there is, in the vicinityof the comers of the mould, provided thermometer pockets 11 into whichthermometers can be inserted for watching the temperature of the water.This will represent the momentary temperature of the concrete and maytherefore be accepted as a measure of the temperature at which thehardening process takes place, and thus as a measure of the time whichelapses before the hardening has proceeded sufficiently far.

FIGS. 3 and 4 show in an 'analoguous manner a mould constructed with aview to producing large, plate-shaped concrete elements by pouring in ahorizontal position, the individual parts having the same referencenumerals as in the embodiment just described. The upper plate 3 serves,as it is shown in FIG. 3, as mould plate and must be supposed to besupple- I mented with edge moulds which may be designed as simple rails,but may also be made as water boxes with.

a view to steam heating by steam being blown into the mass of waterpresent in the boxes.

When the moulds are transported, e.g. suspended in yokes from a crane,difficulties may arise due to movements of the water in the cavities. Tocounteract this, the moulds may, as indicated in FIG. 4, be equippedwith suitable baffle plates 13 in the form of steel plates provided withperforations or other apertures which subdue the passage of the waterwithout impeding temperatureand pressure-balancing flows between theindividual mould sections.

It will be understood that the advantages, gained by the method and thecasting moulds according to the invention, as regards accellerating thehardening process and avoiding damage to the cast concrete bodies willalso obtain although to a lower degree even if the concrete is poured ata lower temperature than the optimum hardening temperature or possiblywithout having been preheated in the concrete mixer.

I claim:

1. A mould for casting objects from hardening masses such as concrete orthe like comprising:

at least one mould member having a mould surface defining at least aportion of a mould cavity into which said hardening mass is placed and aback surface backing said mould surface,

means within said mould member defining at least one water cavitycontacting at least a portion of said back surface and adapted to besubstantially entirely filled with water, and

steam injection means communicating with said water cavity andterminating in at least one steam injector so oriented with respect tosaid water cavity as to establish a circulation of water within saidwater cavity when steam is passed therethrough and to prevent the steamfrom impinging directly upon said back surface, and to maintain thedesired water temperature within said water cavity.

2. A mould as set forth in claim 1 wherein at least one of said watercavities is positioned adjacent to that point of said mould surface fromwhich the disipation of heat during hardening of said mass is thegreatest.

3. A mould as set forth in claim 2 wherein said one of said watercavities is positioned adjacent to the outer peripherial portion of saidmould surface.

4. A mould as set forth in claim 1 further comprising automatic overflowmeans communicating with said water cavity for releasing excess waterfrom said water cavity.

5. A mould as set forth in claim 4 wherein said automatic overflow meanscomprises at least one outwardly opening automatic valve.

1. A mould for casting objects from hardening masses such as concrete orthe like comprising: at least one mould member having a mould surfacedefining at least a portion of a mould cavity into which said hardeningmass is placed and a back surface backing said mould surface, meanswithin said mould member defining at least one water cavity contactingat least a portion of said back surface and adapted to be substantiallyentirely filled with water, and steam injection means communicating withsaid water cavity and terminating in at least one steam injector sooriented with respect to said water cavity as to establish a circulationof water within said water cavity when steam is passed therethrough andto prevent the steam from impinging directly upon said back surface, andto maintain the desired water temperature within said water cavity.
 2. Amould as set forth in claim 1 wherein at least one of said watercavities is positioned adjacent to that point of said mould surface fromwhich the disipation of heat during hardening of said mass is thegreatest.
 3. A mould as set forth in claim 2 wherein said one of saidwater cavities is positioned adjacent to the outer peripherial portionof said mould surface.
 4. A mould as set forth in claim 1 furthercomprising automatic overflow means communicating with said water cavityfor releasing excess water from said water cavity.
 5. A mould as setforth in claim 4 wherein said automatic overflow means comprises atleast one outwardly opening automatic valve.